As its $315,000 Business Lounge V-class and “ultimate city sports car” have displayed, Brabus is not a company that is capable of small-scale thinking. It’s go big or get the hell out of Bottrop. The most recent example is the Brabus Rocket 900 Cabrio, an open-top version of the firm’s extreme S65 AMG coupe that we saw early last year. Altering one of the most powerful production vehicles on the planet might seem outrageous, but that’s exactly the point: to step over the line of a reasonable purpose.

The masterminds at AMG already have a beast in their stable with the S65 convertible. Their twin-turbo V-12 powerplants churn out a claimed 621 horsepower and 738 lb-ft of torque. But Brabus makes that output look like peanuts. After extensive component upgrades and tuning, the Rocket 900 Cabrio claims 888 horsepower and 1106 lb-ft of torque at 4200 rpm, although it’s electronically limited to 885 lb-ft.

Brabus started the aftermarket customization process by enlarging the V-12’s displacement from 366 to 384 cubic inches, or from 6.0 liters to 6.3 liters. A billet-steel crankshaft provides a longer stroke, while billet-steel connecting rods push special forged pistons into cylinders that have been bored out. Beefier turbochargers provide more boost, and specialized exhaust manifolds, a high-performance exhaust, larger downpipes, and free-flow catalysts enhance the breathing. The intake has also been revised with a Brabus-developed module and a new intake manifold with a different air filter box to increase airflow at the same time as cooling it.

All of this extra power is paired with a heartier seven-speed automatic transmission that puts power squarely on the rear wheels with the help of a limited-slip differential that can lock up to 40 percent. Brabus claims the Rocket will launch from zero to 62 mph in 3.9 seconds and is capable of 217 mph, which, if true, could save owners a step in the morning by cleansing their faces of dirt via open-top wind purification.

In addition to the all-important power-pumping components, the 900 Cabrio boasts a bunch of exterior and interior embellishments of the kind we’ve come to expect from Brabus. It has 21-inch forged wheels (9.0 inches up front, 10.5 inches in the rear), with 22-inchers available as an option, and high-performance Continental tires. Buyers can choose between matte or gloss coating over the visible carbon-fiber bodywork, and the kit adds a front spoiler and uses carbon fiber to build the intake surrounds, mirror caps, rear diffuser, and trunklid spoiler. The car was lowered 0.6 inch to complete the sportier look.

Inside, Brabus created parts for its interpretation of a classier and sportier cabin. The doorsill scuff plates have color-changing backlighting, and the paddle shifters, pedals, and door pins are now aluminum. Although completely customizable with different colors and materials, the show car has two-tone Mondial Vanilla and Mondial Black leather with contrast stitching. The interior trim has been replaced with open-pore black-ash wood inlays, but that can be swapped for other woods or materials—perhaps more carbon fiber. What the customer wants, the customer gets. That tailored specification comes at a high cost, we’re sure, but Brabus did not release an official price for this vehicle. Perhaps the company will be more forthcoming when the car makes its debut at the upcoming Frankfurt auto show.